The invention relates to a device for the control of the shutter of a CCD camera supplied with preferably monochromatic light such as laser light from a light source, and more particularly for the control of the shutter of a CCD camera of a light ray marksmanship system, in the case of which the CCD camera photographs dots of light produced by a firearm emitting a light ray directed on a reflecting screen or a television screen so that such dots may be evaluated by a computer and displayed.
CCD (charge coupled device) cameras consist of parallel connected CCD line sensors, which constitute a CCD matrix, in the case of which the area to be displayed is divided up so finely that the impression of a continuous image is created. In accordance with the German standard a CCD camera has a rate of 50 images or frames per second, that is to say 1/2 an image in 20 ms.
CCD cameras are for example employed in light ray marksmanship systems, in the case of which the CCD camera photographs dots of light produced by a light emitting firearm on a reflecting screen or a television screen, which are evaluated by a computer and displayed. Such systems, which mostly operate with infrared light from a laser, have been proposed in the most various different forms, for example in accordance with the German patent publications 2,748,993 A, 3,112,443 A and 3,523,459 A, the European patent publication 146 466 B and the patent publication WO 92/08 093. An infrared laser marksmanship system as described in the patent publication WO 91/09 266 differs from other systems to the extent that the firearm emitting the infrared laser light produces dots on a television screen, on which targets or objects constituting targets may be displayed, the dots of light produced television screen being detected by the evaluating electronic system as hits and being also able to be displayed on the picture screen.
One disadvantage of all known light ray marksmanship systems is that the CCD camera is sensitive to interference in the form of light from the surroundings, which even in the case of operation with infrared laser light rays can not be completely prevented by using an infrared input filter, which is essentially only transparent for infrared light and cuts out visible light.